SetDefaultPrinter call via System Plug-in

[TJK]

Hello

I'm trying to use the System plug-in to call the SetDefaultPrinter function (which I understand is availabel on my Windows XP system), but I'm not having much success.

I found an earlier posting (here) and decided to start by copying the GetDefaultPrinter example, but when I use the following:

System::Call 'winspool::GetDefaultPrinter(t .r0, *i ${NSIS_MAX_STRLEN})'
MessageBox MB_OK $0

I just get an empty message box ($0=NULL).

Similarly when I try the following:

System::Call 'winspool::SetDefaultPrinter(*t "PrinterName")'

The default printer doesn't change.

This is the first time I've use the System plug-in, and though I've read the help and tutorial I'm afraid I don't seem to be grasping it.

Any help and suggestions to point me in the right direction would be gratefully received.

TIA

Tim